INVARIANT ACTIVITY SEQUENCES ACROSS THE MOUSE BRAIN

A central ambition of neuroscience is to identify fundamental patterns of neural activity that are shared across the brain. In the cerebral cortex, candidate patterns for such a canonical role are 50-100 ms sequences of neuronal firing. However, it remains unknown whether these sequences are localized to the cortex or if they extend to regions outside of it, and whether they are stable features or change over time.
To address these questions, we combined chronic recordings in the visual cortex with acute recordings across the entire mouse brain. We used chronic Neuropixels 2.0 probes to track the activity of hundreds of neurons in the visual cortex over several weeks during both visual stimulation and spontaneous activity. To examine the global prevalence of these patterns, we further analyzed acute high-density recordings from the International Brain Laboratory dataset, covering 230 regions across the mouse brain.
In the visual cortex, stimulus responses formed a sequence where neuronal participation depended on tuning, but the timing (delay) was fixed. These sequences interacted multiplicatively with the rate code, persisted during spontaneous activity, and remained stable for weeks even as representational drift occurred. The brainwide recordings demonstrated that similar sequences occur in essentially every region of the mouse brain and are synchronized across regions.
These findings indicate that activity sequences are a stable and ubiquitous feature of neural dynamics. The sequences likely support a canonical computation operating across the brain, organizing brainwide neural activity into coherent temporal structures.